Use the Musical Alphabet (the first seven letters of the English alphabet) to know whether a Note is Sharp or Flat. Verify your Sharp or Flat (Enharmonic Notes) is correct using three simple tests.
Sharp or Flat?
So far we've learned about the specific sequence of whole steps and half steps that make every major scale. We've learned the C Major scale is the only major scale that uses only the white keys on the piano keyboard, and we know all other major scales will use one or more of the black keys. The F Major scale had a Bb and the G Major scale had an F#.
But how do we know the black key used in the F Major scale was a flat and the black key used in the G Major scale was a sharp? The answer lies in the Musical Alphabet. The musical alphabet is the first seven letters of the English alphabet. A, B, C, D, E, F & G. Once these seven letters or note names are used they start over.
Just remember these three simple tests when creating any major scale.